Having trouble tracking down the problem. 91 supercoupe can jump relay and pump will run, if I ground #4 on pressure switch it won't run, I have plugged in another switch, still won't run. It had no power, so I checked it and the relay was full of water. Could it have burned a wire somewhere? Where? About to give up!

ddukes

12-24-2016, 12:32 AM

Changed relay, because everything point to that, still no brakes

sam jones

12-24-2016, 05:37 AM

Good morning

Water in the relay? Is there a story with this condition? Is/was the engine bay exposed to excessive water? Was the replacement relay used or new? If used, one physical check I use is to tap the relay with a screw driver. Does the relay now work? Did you use WD-40 to disperse any water residue on the Hydraulic Pump Motor Relay and Anti-Lock Pressure Switch electrical connectors?

As for the pump motor not working inspect for:

- Corrosion/damage ground wire bus G 121 left front of engine compartment (on the left side of the radiator support next the the drive side light assembly) and G 108 left rear of engine compartment, on brake master cylinder.

- Inspect for corrosion/damage hydraulic pump motor relay connector pin 1 to Anti-Lock Pressure Switch pin 5 of the connector. Ohms check and work your way back to the relay.

The year and model Electrical and Vacuum Troubleshooting manual would be a must.

Good Luck.

davec73

12-24-2016, 01:35 PM

Bad pressure switch. I would look into a conventional brake swap with all the trouble you have had with this and be done with it.

ddukes

12-24-2016, 01:41 PM

Ok finally got power jumping pin 4, this would mean pressure switch, have another , plugged it in, not screwed in the assembly, should it work? Or does it have to be screwed in? Looks like a bitch to change!

Ok finally got power jumping pin 4, this would mean pressure switch, have another , plugged it in, not screwed in the assembly, should it work? Or does it have to be screwed in? Looks like a bitch to change! it has to be screwed in to read pressure I would think

RalphP

12-24-2016, 04:08 PM

It does; so the pump should run with it out (since it turns OFF when the pressure goes high enough.)